Press the button once, and it puts your display to sleep. Press and hold it for a second or two, and the Shutdown / Restart / Sleep dialog appears. Press and hold it for even longer, and your Mac gets completely powered off.

When reinstalling the original software on an older Core 2 Duo MacBook Air the other day, installing the OS itself (in this case, Mac OS X 10.6, which came on a tiny USB stick) went without a hitch. The USB stick's iLife installer, however, kept failing with an unknown error and told me to contact the software manufacturer.

Fortunately, that wasn't necessary.

A look at the installer log (hint within a hint: when in trouble, always check the log) revealed that the culprit was an expired installer certificate. When a certificate expires, OS X doesn't trust it anymore, and thus refuses to install.

All I had to do to work around that error was change the system date back to shortly after the MacBook Air shipped. After traveling back in time, Mac OS X trusted the iLife installer certificate, because it hadn't expired yet back then. So the installation went without a hitch, and after it was done, I changed the date back to the present.

(Note: Newer MacBook Air models let you restore iLife from the Mac App Store. This model, however, predates the Mac App Store, so I don't know whether that would have worked. And I didn't want to use my Apple ID for this anyway, as I'm about to give away the MacBook Air.)

Since I was able to get a MacBook Pro retina last week (you can read my thoughts about it on my blog), I've switched my laptop, for the first time in more than four years, from a 13" to a 15". (My last two laptops were 13" MacBook Airs.)

Discussions about the correct size for a laptop display can be a hostile as those between, say, emacs and vi users. I've noticed especially that many people I know prefer the 11" MacBook Air, whereas for my aging eyes, that display is too small.

So, this seemed like a good question for a poll. Feel free to add any comments you have on the poll page, explaining why your preferred laptop size is the Right Size. Vote in the poll.

When your MacBook Pro switches from integrated Intel graphics to the dedicated GPU, power consumption goes up considerably. Which API calls or program attributes trigger this switch is not totally clear, and programs that you least expect might be draining your battery.

Cody Kriegerís free gfxCardStatus will tell you when a switch occurs and lists which programs are causing this. (It also lets you manually toggle the mode.)

I found out, for instance, that EagleFiler and Twitter both triggered the GPU, significantly reducing the time I could run on battery. (EagleFiler's author is investigating this.) Neither program is particularly graphics intensive, so I'd never have suspected that leaving them up (and hidden) would be draining my battery prematurely.

[kirkmc adds: Since I now have a new MacBook Pro with Retina display (wow, that display is nice!), this hint comes at just the right time. This utility has been around a while, yet it's never shown up here as a hint. Jeff Carlson reviewed it for Macworld last year, so you can read more about it there. One thing I can say about the new MacBook Pro is that the battery life is orders of magnitude better than my late 2010 MacBook Air, and with this utility, I'll be able to use it even longer.]

This is more of an FYI than a deep hint. Apparently in Lion, you can now adjust the screen brightness of your Mac even if it's the secondary display in a dual monitor setup.

I'm using an i7 15" MacBook Pro, and before Lion, if my laptop was set as the secondary display, the brightness buttons on my Apple external keyboard didn't work. The brightness buttons only worked if the display was set as the primary display. Now it works if the laptop is a secondary display.

[crarko adds: This is pretty specific. If folks would be kind enough to try a few other configurations and post the results, that could help this prove to be more generally useful.]

Before Lion it was possible to run an external display off a laptop and have the internal display disabled, even if you opened the lid. This can be useful for a myriad of reason including energy saving and better wifi reception. With Lion the internal display will always turn on when the lid is opened, even if there is already an external display connected.

As it happened to many of you after installing Snow Leopard a couple of years ago the fan of my MacBook went crazy. Even at low CPU temperatures (60 C) it keeps staying at 6200 rpm. The bizarre thing is that putting the MB on sleep and waking it up the rpm stays low. I tried the standard procedure (reset SMC and PRAM, as explained in Apple documents) but nothing changed. Then I've found this page, which makes use of the smc binary of smcFanControl tool. You may find smcFanControl here.

The problem with this hint is that my MacBook DOES heat and keeping a low rpm it overheated causing a crash/shutdown. So, after some investigations on how to read the temperature I came out with the following script, which I stored in /usr/local/sbin/smcFanReset.

The maximum allowed rpm by the SMC is greater than 6200. One may want to raise it at his/her own risk. Obviously it will be much louder.

Do not expect your MacBook to be much cooler. Just more silent.

Again, use this at your own risk. The values I have set fit with my regular usage. The temperature goes above 75 C when watching videos and stuff and as long as it didn't hit the 80+ C a lower rpm didn't overheat the MacBook. Also the one minute delay is not much to have a drastic raise on CPU temperature. I have been running this for few days now and it is pretty stable.

I just just got a new MacBook Pro 15", and was finishing the installation of all my software. I installed FaxSTF (Smith Micro Fax) which was the last software to install.

I rebooted and looked in the Finder and could not find Fax Pro. I then reinstalled it and at the end it just crashed. After sending an email off to the software vendor for support, I tried to plug in the Apple Fax adapter and to my surprise received this message: 'This computer will not allow Fax.'

[crarko adds: Can anyone confirm or deny this? I wouldn't be surprised if it's true. What does the 'Print & Fax' System Preference show on these models?]